Telegraph receiving station



8 Sheets-Sheet l W. E. WALKER ET AL TELEGRAPH RECEIVING STATION sept. 3, 1957 Filed June 21, 1955 Sept. 3, 1957 w. E. WALKER ET AL 2,805,279

TELEGRAPH RECEIVING STATION Filed June 2l, 1955 8 Sheets-Sheet 2 mms. 1

l I INVENTOR5 #tikaf/E alr l: LKML/12mg@ Sept. 3, 1957 w. E. WALKER ETAL TELEGRAPH RECEIVING STATION 8 Sheets-Sheet 3 Filed June 21, 1955 SSR@ b ill@ Y n NNW Sept. 3, 1957 w, E, WALKER ETAL 2,805,279

TELEGRAPH RECEIVING STATION 8 Sheets-Sheet 4 Filed June 2l, 1955 lll'lllll IIIHIIIIII Sept. 3, 1957 W, E, WALKER ET AL 2,805,279

TELEGRAPH RECEIVING STATION 8 Sheets-Sheet 5 Filed June 2l. 1955 Sept- 3, 1957 w. E. WALKER ET Al. 2,805,279

TELEGRAPH RECEIVING STATION Filed June 21, 1955 a sheets-sheet e INVENTORS Sept. 3, 1957 Filed June 2l, 1955 W. E. WALKER ETAL TEM-:GRAPH RECEIVING STATION 8 Sheets-Sheet '7 Sept. 3, 1957 w. E. WALKER ETAI- 2,805,279

TELEGRAPH RECEIVING STATION Filed June 21, 1955 8 Sheets-Sheet 8 IN VEN TOR5 Hrw/ff United Sttes Patent TELEGRAPH RECEIVEG STATION William E. Walker, Brooklyn, and Claude L. Kennedy, Patchogue, N. Y., assignors to Radio Corporation of America, a corporation of Delaware Application .lune 21, 1955, Serial No. 516,8] 6

12 Claims. (Cl. 178-2) This invention relates to receiving stations of the type used in telegraph communication systems and, more particularly, to a telegraph receiving terminal station of a type found at a central oiiice and which is capable of distributing messages to a plurality of suitable receiving devices in a prearranged manner.

A telegraph communication system includes a terminal transmitting station and a terminal receiving station electrically interconnected by suitable transmission lines. The transmitting station generally includes a number of telegraph transmitters, each of which is operated to transmit messages over the transmission lines to receiving equipment at the receiving station.

Various arrangements have been devised for controlling the feeding of messages from the output circuits of the transmitters to the receiving equipment at the receivingstation. In one type of arrangement known as a multiplex system, the messages from the transmitters are sequentially transmitted over a single transmission line. This type of arrangement in which the time of the transmission line is sequentially allotted to the diiferent transmitters is known as time division multiplex transmission. Means are provided at the receiving station for separating the various messages from the signal transmitted over the single transmission line and for distributing them among a plurality of receiving devices. The receiving devices may be located at a central oiiice or may be individually located at subscriber stations remote from the central office which services them. In either case, each of the receiving devices represents an individual receiving station to which messages may be sent by the transmitters at the transmitting station. T he distribution of the messages at the terminal receiving station may be controlled synchronously with the operation of multiplexing equipment at the transmitting station or may be controlled by information forwarded over the single transmission line bythe terminal transmitting station, as, for example, Arouting information preceding each message transmitted over the line. In another and simpler type of arrangement known as simplex, the output circuit of each transmitter is operatively connected directly to a particular one of the receiving devices at a receiving station by an indi- 'vidual transmission line. The full capacity of each of the lines interconnecting the transmitting station and receiv- Eing station is occupied by the messages transmitted by a single one of the transmitters.

Both types of arrangement have advantages when used 'in particular applications. Under normal operating conditions, service can be supplied to subscribers by utilizing :the multiplex type of transmission. Further, a separate :transmission line may not be available for use by each fof 4the ,transmitters in which case the use of the multiplex l:type of transmission is desirable and necessary. By the `use of high speed transmission, a number of messages :can be transmitted over a single transmission line and distributed to receiving devices by the distributing equiplrnent at the receiving station in a short period of time.

The time of the transmission line is sequentially allotted 'to each transmitter, permitting each of the transmitters to 2 transmit messages to a particular receiving device operated through the distributing equipment at the receiving trminal station. However, during certain periods of operation, the volume of traiiic destined for a particular receiving device from one of the transmitters may greatly exceed that destined for the remaining receiving devices from the other transmitters. If the single transmission line is operating at or near full capacity, it will not be possible to speed up the rate of transmission to accommodate Vthe increased volume of trafc destined for the particular receiving device. During such periods, Ythe use of an individual transmission line between the transmitter and the receiving device is more desirable. Assuming that additional transmission lines are available, by connecting the output circuit of the transmitter handling the increased volume of traiiic directly to a particular receiving device at the receiving station through an individual transmission line, the full capacity of the-line may be occupied by the traiic forwarded by that'transmitter. Inasmuchas the transmitter is now operating over the full capacity of a transmission line rather than a portion of the capacity, as would be the case in multiplex transmission, the rate of transmission will-be greatly increased and the increased volume of traiiic maybe handled satisfactorily.

A telegraph system in accordance with the invention includes means for controlling the transmission of the messages transmitted by each of the transmitters at the terminal transmitting station over a single transmission line, if multiplex transmission is adequate to handle the volume of traiiic, and, particularly, when only one transmission line is available. The system of the invention also includes means for controlling the transmission of messages when the volume of traiiic destined for a particular one of the receiving devices or each of the receiving devices at the receiving terminal station increases to such an extent that the traic cannot satisfactorily be handled by the use of multiplex transmission. Assuming that a suiiicient number of transmission lines are available, a separate transmission line is assigned to handle the messages destined for the particular one or each of the receiving devices. The system should, therefore, include means for utilizing multiplex transmission, multiplex and simplex transmission or simplex transmission only, the particular type of transmission used being determined by the volume of trafiic, availability of transmission lines and other circumstances existent during the operation of the system.

Accordingly, it is an object of this invention to provide an improved telegraph receiving station capable of distributing messages to suitable receiving devices in aprearranged manner.

It is av further object of this invention to provide a novel -type of telegraph receiving station capable of distributing messages which are fed to the receiving station in either multiplex, simplex, or both multiplex and simplex fashion to suitable receiving devices in a prearranged manner.

The invention in elect comprises a combination of three different types of telegraph communication systems, namely, a multiplex transmission system, a simplex transmission system and a transmission system including both a multiplex and simplex transmission system. Means are provided at the transmitting terminal station under the control of an operator for enabling a selection of either type of transmission system.

A transmitting terminal station and a receiving terminal station are interconnected by a plurality of transmission lines. The transmitting terminal station includes a number of telegraph message transmitters. A telegraph transmitter set to transmit routing information is associated with each of the message transmitters, f

attenere' .In ,tbe .tiret .type .of transmission, .tbe message and routing transmitters are operated to transmit messages sequentially over a single transmission line. A common linev is seqnentially ,assigned to .tbe .oiiierent nte se transmitters tot the transmission of messages .tbereovetv Tbe messages transmitted by each of the messa e transmitters .are preceded by tbe renting intron jtransrnitteld by one lof the routing transmitters, .a fontina transmitter being operatively associated .with ,nach gf Vthe message transmitters. The routing informa- .'tion precedes a message and indicates the particular receiving device which is to receive the .message- The transmitters `are `sequentially operated to transmit messages over the `line on a message by message basis.

.In another type Y.o transmission, the control equipment at the transmitting terminal station enables a single one of the plurality of message transmitters to transmit messages yover ,an individual transmission line, and the vremaining message transmitters and the routing transmitters associated therewith to operate to transmit messages .in mnltiplexk fashion sequentially over a second `transmission line.

"if .the necessary transmission lines are available, the .control equipment at. the transmitting station may also b e made to operate the message transmitters so that each message transmitter transmits messages over an individualV transmission line, in which case a separate transmission line is assigned to each message transmitter. In this; instance the full capacity of each of the lines is occupied by the messages transmitted by the particular one ofthe message transmitters connected thereto.

The receiving station is constructed to properly handle the messages transmitted over the transmission lines in any one of the types of transmission possible. The receiving station includes a receiving director unit to which are .Connected the transmission lines extending from the output circuits of the transmitters at the transmiting station.4 `A plurality of receiving devices, such as telegraph printers or rcperforators, are operatively connected to the output circuits of the director unit. Included in the receiving director unit is a switching circuit and a selector *,CQntrOl. The selector control includes a number of operating positions. By settingthe selector control at one of the positions, the switching circuit of the receiving director unit is controlled to operate in a predetermined sequence to provide the proper termination for the transmission lines in the receiving station. The selector controli controls the operation of the receiving director unit lto distribute the messages received over the transmission lines to the receiving devices when any one of the types of transmission available is utilized. It will be remembered that, in oneV type oftransmission, the message and routing transmitters may be sequentially operated to transmit messages over a single transmission line. Each message transmitted by the message transmitters is then preceded by routing information. The selector control of the receiving director unit is set at the position correspondng to this type of transmission. The switching circuit of the director unit operates in a predetermined sequence to separate the messages as they are received over the line and to feed them to the receiving devices vin accordance with 'the routing information preceding typerof' transmission and the switching circuit of the receiving director unit operates in a predetermined seduence to connect one of the receiving devices at the receiving station directly to the transmission line which is assigned f'ull time to the single message transmitter.

The switching circuit also operates to separate the messages transmitted over the second transmission line by the remaining message transmitters and the routing transmitters associated therewith, and to feed the messages to the intended receiving devices at the receiving station in accordance with the routing information preceding each message. A proper termination is provided for the messages transmitted over both of the transmission lines.

In the remaining type of transmission, each of the Illessage transmitters may be operated to transmit messages over individual transmission lines assigned thereto. The selector control of the receiving director unit is then set at still another position corresponding to this type of transmission. The switching circuit of the receiving director unit is operated in a predetermined sequence to connect a separate one of the receiving devices at the receiying station directly to cach of the transmission lines. Each of tbe message transmitters is operatively .connected by one of tbe transmission lines .directly to an individual receiving device at the receiving station The full capacity o f .each of the transmission lines will be occupied by the messages transmitted by the. particular transmitter kc.tmneetetl thereto .and the transmitters may be operated ,continucnsly and simultaneously yover tbc respective lines A more detailed description of the invention follows with reference to the accompanying drawing in which:

Figi is a block diagram of a telegraph communication system constructed according to the invention;

Figs. 2g, 2b, v2 c and 2d disclose a circuit diagram of one embodiment of a transmitting terminal station suitable for use in the system shown in Fig. l;

Fig. 3 is ablock diagram depicting the manner in which Figs. 2a, 2b, 2c and 2d are to be assembled;

Figs. 4a and 4b disclose a circuit diagram of one embodiment of a receiving terminal station suitable for use in the system shown in Fig. l;

Fig. V5- is a block diagram depicting the manner in which Figs. 4a and 4b are to be assembled;

Fig. 6, is a timing diagram given in explanation of the sequence of operation of the connting circuit located at the receiving terminal station.

Referring to Fig. 1, there is shown a block diagram of a telegraph communication system constructed according to the invention. Three groups of transmitters arieshown, namely, groups A, B and C. The terms group of transmitters and transmitter group, as used in the specification, are to be considered as referring to a telegraph transmitting device. The transmitting devices may ali be located at a central o fce or may be individually located at subscribers, stations remote from the central o ice which services them. In the embodiment of the invention` to be described, each of the transmitting devices includes four separate telegraph transmitters. The rst, transmitter l, is operated to transmit routing information. The second transmitter 2 is a numbering transmitter and transmits one of a sequential group of numbers preceding each message transmitted by the group, identifying the message for purposes of record keeping and so on. The third transmitter 3 is a message transmitter and the fourth transmitter 4 is also a message transmitter. The sequenceV of operation of the transmitters in each transmitter group follows the order given above. The routing transmitter 1 will be operated rst, followed by the numbering transmitter 2 and, thereafter, one of the message transmitters 3 or 4. Each of the transmitter groups will be operated in the same sequence. The four transmitters of each group A, B. and C, twelve transmitters in all, will be operatively connected to a transmitting control unit 90. Included in the control' unit 90 is a selector control 6, including wiper 5 and four operating positions. Three transmissln lines 7, 8 and 9 are connected to the output circuits of the transmitting control unit 90.

When the wiper 5 of, the selector control 6. is set at position 1,'the messages transmitted by each of the three groups of transmitters A, B and C will be sequentially transmitted over line 7 to a tape reperforator-distributor 10 at a receiving station on a message by message basis. Each message transmitted by each group will include routing and numbering information transmitted by transmitters 1 and 2 and a message transmitted by message transmitter 3 or message transmitter 4. Only one of the transmitter groups will be operated at a time. Position 1 of selector control 6, therefore, controls the transmitting control unit 90 to bring about the multiplex operation of the system.

When wiper 5 is set at position 2 of the selector control 6, the transmitting control unit 90 will be operated to connect the output circuits of the transmitters 1 through 4 of group A to line 8. The transmitters 1 through 4 of group B and the transmitters 1 through 4 of group C will again be sequentially connected to line 7. At position 3, the transmitting control unit 90 will be operated to connect the output circuits of the transmitters 1 through 4 of group B to line S. The transmitters 1 through 4 of group A and the transmitters 1 through 4 of Group C will be connected to line 7. At positions 2 and 3 of selector control 6, therefore, both multiplex and simplex transmission will be used. In both cases, the time of line 7 will be occupied by messages transmitted by at least two of the groups of transmitters. The transmitting control unit 90 will act as multiplexing equipment to sequentially feed the messages from the two groups of transmitters over the line 7. In both cases, line 8 will be occupied by messages transmitted by only one of the transmitter groups. The line 8 will be connected to the output circuits of the transmitters of the group through the transmitting control unit 90 and simplex transmission over line 8 will result.

When the Wiper 5 of the selector control 6 is set on position 4, the transmitting control unit 90 will be operated to connect the output circuits of transmitters 1 through 4 of group A to line 8. The output circuits of transmitters 1 through 4 of group B will be connected to line 9 and the output circuits of transmitters 1 through 4 of -group C will be connected to line 7. The full capacity of each of the transmission lines, lines 7, S and 9, will be occupied by the messages transmitted by the par ticular transmitter group A,-B or C connected thereto.

Line 7 is connected to a reperforator-distr'ibutor 10 at a receiving terminal station, the output of the reperforator-distributor 10 being fed to a receiving director unit 11. Lines 8 and 9 terminate at the receiving director unit 11. Four receiving devices 12, 13, 14 and 1S are operatively connected to the output circuits of the receiving director unit 11. The receiving `devices may be printers, reperforators or other types of telegraph recording equipment. vA selector control 16, including a wiper 5 and four operating positions, is included in the receiving-director unit 11, the sequence of operation of the unit 11 being determined by the setting of the selector control. The positions of the control 16 correspond to the positions of the selector control 6 in the transmitting control unit 90. When the control 6 is set on position 1, the messages transmitted by the three groups of transmitters A, B and C will be sequentially fed over line 7. Control 16 of the receiving director unit 11 will also be set on position l. The operation of the receiving director unit 11 will be controlled to distribute the messages received by the reperforator-distributor 10 through the receiving director unit 11 among the receiving devices 12, 13, 14 and 15 in accordance with the routing information preceding each message, indicating the particular receiving device to which the following message is sent. For example, all the messages transmitted by the transmitters of group A will be fed to receiving device 12, messages transmitted by the transmitters of group B will be fed to receiving device 13 and the messages transmitted by the transmitters of group C will be fed to receiving device 14.

If the wiper 5 of selector control 6- of the transmitting control unit is set on position 2, the transmitting control unit will be operated to connect the output circuits of the transmitters of group A to line 8, the output circuits of the transmitters of groups B and C being sequentially connected to line 7. The Wiper 5 of selector control 16 of receiving director unit 11 will also be set on position 2. The director unit 11 will be operated to feed the messages transmitted over line 7 by the transmitters of group B to receiving device 13 and the messages transmitted over line 7 by'the transmitters of group C to receiving device 14 in much the same manner as it did when the wiper 5 of the control 16 was set on position 1. The operation of the receiving director unit 11 will connect the receiving device 12 directly to the line 8 through the director unit. The output circuits of the transmitters of group A will be operatively connected to the receiving device 12. The full capacity of line 8 will be occupied by the messages transmitted by the transmitters of group A and the transmitter group may be operated at the maximum rate of transmission possible.

When the wiper 5 of selector control unit 90 is set on position 3, the transmittingcontrol unit 90 will be operated to connect the output circuits of the transmitters of group B to line 8, the output circuits of the transmitters. of groups A and C being sequentially connected to line 7. The wiper 5 of selector ocntrol 16 of receiving director unit 11 will also be set on position 3. Messages transmitted over line 7 by the transmitters of group A will be fed by the operation of the receiving director unit 11 to receiving device 12 and the messages transmitted over line 7 by the transmitters of group C will be fed to receiving device 14. Receiving device 13 will be connected by the operation of the receiving director unit 11 through the unit to line 8. The output circuits of the transmitters o-f group B will be operatively connected to receiving device 13 over line 8. The full capacity of the line 8 will be occupied by the messages transmitted by the transmitters of group B and the transmitter group may be operated at the maximum rate of transmission possible.

The operation of the system may require that each .transmitting group be connected directly to a receiving device over an individual transmission line. In such a case, all three transmitting groups will be operated at the maximum rate of transmission possible, the full Acapacity of each of the lines being occupied by the messages transmitted by the particular transmitting group connected thereto. The wiper 5 of selector control 6 of transmitting control unit 90 will be set on position 4. The transmitting control unit 90 will be operated to connect the output circuits of the transmitters of group A to line 8, the output circuits of the transmitters of group B to line 9 and the output circuits of the transmitters of group C to line 7. The wiper 5 of selector control 16 of the receiving director unit 11 is also set on position 4. The receiving director unit 11 will be ope-rated to connect receiving device 12 to line 8, receiving device 13 to line 9 and receiving device 14 to line 7. The output circuits of each of the groups of transmitters Will be operatively connected to a single one of the receiving devices. The full capacity of each of the lines will be occupied by the messages transmitted by the particular transmitting group connected thereto and each of the groups of transmitters can be simultaneously operated at the maximum rate of transmission possible.

When the transmitter groups are being controlled in multiplex operation, the routing information, as received by the reperforator-distributor 10, preceding certain of the messages, may be incorrect due to, for example, breakdown in the transmitting equipment. This will prevent the receiving director unit 11 from properly feeding the message following the incorrect routing information to the intended receiving device. The receiving 'director unit, if desired, may be operated to terminate such mesagsoaro sg'ei's" eceivingdevice 14 The messages' transmitted bytriisiiiitterfg'rop C may" be t'errriinatediin receiving dieV ce 155 rather thanl device'. f4; as occurs when only' thlree fecving devices 12, 13" and1` 1'4 are' used. It is be non that'the use" of-four'reeeiving devices isYr anI n to theyuse df three and that either arrangement riay he sed. I'

7(,)rie embodiment of a transmitting terminal station suitablr'foiyse in' the system` shown in` the rblock diagram of" ig. l i's'A shownL ir'Figfs'. 2d, 2li', 2c and 2d. Reference' also made" fo'Fig. 3" which depicts the man-ner in which the Figs. d2h', 2lb, 26 and 2dk are'to'tble assembled. Three 'gjrjps or transmitters A, B- amr C are shown in Fig. 2a, aen grbup including a raining' transmitter 1', numbering zitter niessagetfnsrr'iitter' 3' and message trans- 4, The transmitters' are operatively connected to ai switc irig' circuitvfhich includes tlrree switching sections A Ltnig'. 215), B ,(aig. ze) eine (Fig. 2d), each group 6r transmitters being operated-by ene of the switching sections. The three switching sections are identical in construction and, for ease of description, the correspond ing lie-lays iii each section have been given the same letter designation. The' relays of switching section A operating g'roup A of the transmitters are indicated by the ltte A preceding the letter designation, the relays of svi/itching section B operating group B of the transmitters being indicated by the' letter B preceding the letter designation and the relays of switching section C operating gl'rop C of the transmitters being indicated by the letter C preceding tlieletter designation. The operation of the three giou'ps of transmitters by the respective switching sections of the switching circuit will in each case be the same. The sequence 'of operation ofthe relays in each section will also be the same. Individual control of the groups of 4transrnitiers is. exercised vby a selector control i6, iie'rr'jd y'to in connection with Fig. l, which controls lthe lo/"e'all operation of the switching circuit. The con- Vtl `6 includes fifteen selector switches 20 through 34, 'each of the selector switches including four contact posiytions and a wiper 5. The Vwiper of each 'of the selector switches and the Wiper 5 of selector control 6 are connected to and idriven by a 'common shaft 35. Therefore, as the shaft 35 is rotated from one position to the next by "the operation of Vthe wiper 5 'of control 6, the wipers of 'all of lthe selector switches, 20 through l34, will be simultaneously 'positioned in accordance with the movement of Ythe shaft. It is 'the 'positioning of the wiper S lof the selector control 'Gand the resulting positioning of thiefvvipers 'of selector switches 20 'through 34 which contrlsfth operation 'ofthe various switching sections 'of the "'sii'vithing circuit ofpthegtr'an'smitting control `unit and, ,thfeforeh'e operation ofieach group of fthe transmitters. A' The wipers 5 Vofthe selector switches and the Wiper 5 of Ythe selector control are 1shown "in Figs. 2a, 2b, 2c and 2d fas being conect'ed =together 'by a mechanical connection nasriich'a's "the operation of'each of the three switching sections ofthe switching circuit 'of the `transmitting control unit is the saine, only the 'operation of switching section A, Sho-Wh in Fig. 2b, will be described. HOW- Aever, `it is to Vbe"understood that the Ysequence of oper- 'ation is exactly vthe"s'a'1n`e': 'in switching sections B and C 'of the switching circuit. l It will be vassumed that an yop'f'rator Wishes to transmit 'a 'message bymessage transinitter 3 of 'group ofthe transmitters. It will'be further assumed that selector control switch'is set on position l and, therefore, that multiplex transmission is to 'be used. A perforated message tape is inserted in the sensing contacts of the transmitter 3, closing the conlt'cts 36 vwhich will remain closed during the transmission of a message from the message transmitter. Upon the closiiieof contacts 36, a path will be completed from 'grorid tothe positive terminal"92 of 'a source of poten- "tiaLnotshown, through contacts 36,' lead 37,'the winding l'ofrel'yAH,v contacts 2 and 'armature 1 'of 'transfer con- `@a facts A112 eff-relay A-I, break contactsv B111 of relay: BI, break' contacts BH1 of relay' BH, lead 91' andi lead; 35'. The t'e'rrr'i` ground, as usedin the speciication, isf to be consideredasaLpoi-ntoff zeroor ti-Xed reference poten tial. Upon' the energization of relay AH, a pathY will'- be completed from; ground to the positive terminal 9-2 through makec'ontactsAH, armature 1 and contact- 3 of transfer contacts 4AC3 of relay AC, armature 1 and contact 3 oftransfer contacts AES of relay AE, break contacts AG2- of relay AG, the'windingI of relay AA, wiper 5 and position l of selector switch 20, break contacts CD1 of relay CD, break contacts CB1 of relay CB and break contacts CAI of relay CA. Relay AA is energized and a path will be completedfrom ground to the positive terminal 92 through the winding of relay AX, contact 3V and armature 1 of transfer contacts AAZ of relay AA and lead 37. Relay AX is energized and a path will be` completecl from ground to thev positive terminal 92 through the Winding of relay A-B, make contacts AX1 of relay AX and lead 38; VWhenr relay AB is energized, a path will be completed'from ground to the positive terminal 92 through contacts 39 of the routing transmitter 1 of transmitter group A, lead 40, the winding of relay AC, contact 2 and armature 1 of transfer contacts ADI of relay AD, lead 41, position l and wiper 5 of selector switch 21, make contacts AB-1 of relay AB and lead 38. Relay AC will be energized and make contacts AC2 of relay AC Will close providing a holding circuit for the relay. Armature 1 of transfer contacts AC3 will disengage contact 3 and engage contact 2 of the transfer contacts. The ground connection to the Winding of relay AA will be disconnected and, therefore, relay AA will be inactivated. Upon the inactivation of relay AA, armature 1 of transfer contacts AA2 will disengage contact 3 and engage contact 2 of the transfer contacts. The winding of relay AX will be disconnected from the positive terminal 92 and will be inactivated. Upon the inactivation of relay AX, make contacts AX1 of relay AX will open disconnecting the positive terminal 92 from the winding of relay AB, inactivating relay AB. Upon the inactivation of relay AB, a path will be completed from ground to the positive terminal 92 through the winding of the release magnet 42 of the routing transmitter 1 of transmitter group A, lead 43, make contacts AC4 of relay AC, break contacts ABZ of relay AB, Ycontact 2 and armature 1 of transfer contacts AA2 of relay AA and lead 38. Relay AC Will be held `energized through make contacts AC2 of the relay 'which connect the winding of the relay to the positive terminal -of a source of potential.

The winding of the release magnet 42 being energized, 'the routing ltransmitter will be operated to forward routing information to the distributing contacts 44 of the transmitter. The routing information may be perforated 'in 'a continuous tapefed to the'routing transmitter or may be obtained in any other suitable manner. When the Atransmission of the routing information has been cornlpleted, the 'contacts 39 will be momentarily opened. pon the opening of the contacts 39, 'the ground connection to the Winding of relay AC via lead 40 will be disconnected and relay AC will `be inactivated. When relay AC is inactivated, make contacts AC4 of the relay will open disconnecting the ,positive terminal .92 from the winding ofthe release magnet 42 of the routing transmitter 1. The winding willno longer be energized and 4the operation of the routing transmitter 1 Will cease.

It will be .remembered that upon .the energization of relay ACgarmature .-1-:of transfer contacts AC3 ofrelay 'ACdisenga'ged'contact -3 and engaged contact 2 ofthe transfercontacts. Theoperation of the transfer contacts fcompletes facp'athlfroms ground .to 4'the'. positive .terminal 9,2 'through makecontacts :of vrelay AH, armature ;-1 land 'Contact '2fof Stransferfcontacts AC3! of frelay AC, Athe winding"ofk relay ADetndileadBS. Relay yis .energized *and-a' holding circuit for relay AAD Willbeestablishedby engage contact 3 of the -transfer contacts.

the closing ofmak contacts AD2 ofthe relay, providing a ground connection Yfor the winding of the relay. After the routing transmitter has completed the transmismission of routing information and relay AC has been inactivated, only two relays of the switchingsection A of the switching circuit will remain activated, namely, relays AH and AD.

When relay AC is inactivated, the ground connection will once again be connected to the winding of relay 'AA through the armature 1 and contact 3 of the transfer contacts AC3 of relay AC. Relays AA, AX and AB will be energized in the same manner as outlined above. However, when relay AB operates, relay AC will not be operated, as previously occurred. This is so because the energization of relay AD caused armature 1 of transfer contactsADl of relay AD to disengage contact v2 and engage contact 3 ofthe transfer" contacts. The operation of relay AB cannot complete a path from the positive terminal 92 to ground through the winding of relay AC. However, when relay AB operates, a path will be completed from the positive terminal 92 to ground through lead 38, make contacts ABlof relay AB, wiper 5 and position l of selector switch 21, lead 41, armature 1 and contact 3 of transfer contacts AD1 of relay AD, break contacts AC1 of relay AC, armature 1 and contact 2 of transfer contacts AFI of relay AF, the winding of relay AE, lead 45 and closed contacts 46 of numbering transmitter 2 of transmitter group A. Relay AE will be energized and the closing of make contacts AE1 of the relay will establish a holding circuit for the relay. Armature 1 of transfer contacts AES of relay AE will disengage contact 3 and engage contact 2 of the transfer contacts. The ground connection to the winding of relay AA will be disconnected and relay AA will be inactivated. Upon the inactivation of relay AA, relays and AB will also be inactivated, as outlined above. At the same time, a path will be completed from ground 'to the positive terminal 92 through make contacts AH1 of relay AH, armature 1 and contact 3 of transfer contacts AC3 of relay AC, armature 1 and contact 2 of transfer contacts AES of relay AE and the winding of relay AF. Relay AF will be enregized and the closure of make contacts AF2 of the relay will establish a holding circuit for the relay. A further path will be completed from ground to the positive terminal 92 through the winding of the release magnet 47 of the numbering transmitter '2 of transmitter group A, lead 48, make contacts AE4 of relay AE, break contacts AB2 of relay AB, contact 2 and armature 1 of transfer contacts AAZ of relay AA Yand lead 38. The winding of the release magnet 47 of the numbering transmitter 2 of transmitter group A will be energized and the numbering transmitter 2 will lbe operated to forward oneV of asequential group ,of 'numbers to the distributing contacts 49 of the numbering transmitter 2. When the transmitter has completed vthe transmission of a number, the contacts 46 will be momentarily opened, disconnecting the ground connection to thewinding of relay AE via lead 45. Relay AE will be inactivated. The inactivation of relay AE causes make contacts AE4 of relay AE to open, disconnecting the positive terminal 92 from thewinding of the release magnet 47 of the numbering transmitter. vThe numbering transmitter will cease operation. At this point, relays AD, AF and AH will be the only relays energized inthe switching section A of the switching circuit. v

When relay AE is inactivated, armature 1 of transfer contacts AES ofrelay AE will disengage contact 2 and The release of the transfer contacts AE3 will again connect the ground connection to the winding of relay AA, and relay IAA will be energized. Relays AA, AX and AB will be energized in the same manner as outlinedabove However, when relay AB is energized, neither relay AC no r relay AE can now be energized,- aspreviousl-y occurred.

10 Relay' AC cannot "be energized due to the' Yenergizatifon of relay AD which causes the armature 1 of transfer contacts AD1 of relay AD to disengage contact 2 and engage contact 3 of the transfer contacts. Relay AE cannot be energized due to the energization of relay AF which causes the armature 1 of transfer contacts AFI of relay AF to disengage contact 2 and engage contact 3 of the transfer contacts. However, a path will be completed from the positive terminal 92 to ground through lead 38, make contacts ABI of relay AB, wiper 5 and position 1 of selector switch 21, lead 41, armature 1 and contact 3 of transfer contacts AD1 of relay AD, break contact AC1 of relay AC, armature 1 and contact 3 of transfer contacts AF1 of relay AF,` break contacts AE2 of relay AE, the winding of relay AG and make contacts AHI of relay AH. Relay AG will be energized and the closing of make contacts AG1 will establish a holding circuit for the relay. Break contacts AG2 of relay AG will open, disconnecting the ground connection to the winding of relay AA, inactivating relay AA. Relays AX and AB will also be inactivated in the same manner as outlined above. Upon the inactivation of relay AB, a path will be completed from ground to the positive terminal 92 through the winding of the release magnet 50 of the message transmitter 3' of transmitter group A, lead 51, make contacts AH3 of relay AH, make contacts AGS of relay AG, break contacts AB2 of relay AB, contact 2 and armature 1 of transfer contacts AAZ of relay AA and lead 38. The winding of the release magnet 50 of the message transmitter 3 will be energized causing 4the transmitter to operate. The message to be transmitted will be forwarded to and retransmitted by the distributing contacts 52. When the transmission of the Ymessage has been completed, the contacts 36`of the message transmitter 3 of transmitter group A will be opened indicating the completion of the transmission. When contacts'36 open, the ground connection to the winding of relay AH via lead 37 is disconnected and relay AH will be inactivated. The inactivation of relay AH will cause make contacts AH1 of relay AH to open, disconnecting the ground connection -to the windings of relays AG, AF and AD. All of the `relays in the switching'sec'tion A will be inactviated and the switching circuit will be returned to its original condition. g

In sequentially controlling the operation of the transmitters ofl transmitter group A, provision Vmust be made whereby the energization of Vthe release magnet of Aa transmitter does not take place before the previous transmitter has completed the distribution of the niessage to be transmitted thereby. The sequence of operation, relay AA operated, relay AX operated, relay AB 'operated-,vrelay AC, AE or AG operated, relay AA released, relay AX released, relay AB released, provides the necessary time interval for the transmission from the 'preceding transmitter to be completed before transmission from the next is started. To insure that the proper time interval exists, relays AB and AX are slow operateslow release relays. `There is provided enough delay switching from one transmitter to the neXt to allow for the complete operation of each transmitter. The transmitters will be sequentially operated by the switching circuit so that no overlap of the respective messages transmitted therefrom will occur. If message transmitter 4 of the transmitter group A were to have been operated instead of message transmitter 3 of the group, the exact same sequence of operation of the switching section A of the switching circuit would have followed with one exception. The closing of the contacts 53 of the message transmitter 4 by the insertion of a perforated message tape into the sensing contacts of the transmitter will operate relay AJ via lead 54 in the same manner that relay AH was operated via lead 37 bythe closing of contacts 36 of message transcompleted `the transmission of a message from message transmitter 3 of the group. n

Upon the energization of relay BH or B1 of 'switching section B `of the switching circuit, a path will be completed from ground to the winding of relay BA through make contacts BH2 of relay BH or make contacts B12 of relay B1, armature 1 and contact 3 of transfer contacts BCS of relay BC, armature 1 and contact 3 of transfer contacts BES of relay BE and break contact BG2 of relay BG. However, the path from the winding of relay BA to the positive terminal 92 through wiper 5 and position 1 of selector switch 2S, break contacts ADS of relay AD, break contacts ABS of relay AB and break contacts AAS o f relay AA will not be completed due to the open condition of one of the contacts in the path. As mentioned above, the sequence of operation of switching section A of the switching circuit is such'that at least one of the relays AA, AB or AD will be energized at all times during the operation of switching section A and, therefore, one of the break contacts AAS, ABS or AD3, in the path of the winding of relay BA, will be open. Switching section B of the switching circuit cannot be operatedvand, therefore, transmitter group B will not be placedrin operation.

When relay AH operates, armature 1 of transfer contacts AH2 of relay AH will disengage contact 2 -and engage contact 3 of the transfer contacts. The operation of the transfer contacts AH2 of relay AH will complete a path from the winding of relay AH to the positive terminal 92 through lead 58, lead 91 and lead S8. A`holding circuit is established for the relay AH. When relay BH or B1 of switching section B of the switching circuit is energized, break contacts BH1 of relay BH or break contacts B11 of relay B1 in the original operating circuit of relay AH will open. However, relay AH will continue to be 'energized through the holding circuit established by'- lead SS-which removes the break -contacts B11 and b r'e'ak contacts BH1 from the operating path of relay AH.

-As soon as message transmitter 3 of transmitter group A- has completed the transmission of a message, relay AH will be inactivated. Upon the inactivation of relay AH, all of the relays in switching section A of the switching circuit,` then operated, will also be inactivated. Relay AD will be inactivated closing break contacts AD3 of the relay. V A path is then completed from the winding of relay BA of `switching section B to the positive terminal 92 through the break contacts ADS, ABS and AAS. Relay BA will be energized and the sequence of operation outlined in connection with switching section A will occurl in switching section B bringing about the operation of transmitter group B. Upon the inactivation of relay AH, armature 1 of transfer contacts AH2 of relay A H will disengage contact 3 and engage contact Z of the transfer contacts. The holding circuit for the relay AH provided by the lead 58 will be disconnected from the winding of relay AH and the break contacts BH1 of relay BH and break contacts B11 of relay B1 will be reinserted in the operating circuit of the relay. As one of these contacts isl now open due to the operation of relay BH or B1 of switching section B of the switching circuit, neither relay nor A1 can be energized and, therefore, transmitter group A cannot be placed in operation. Break contacts AH4 of relay AH in the operating circuit of relays CH and. CJ of switching section C of the switching circuit will be closed. It is evident, in view of the above discussion, Vthat during the period that switching section B is operating to control the operation of transmitter group B, switching 4section C of the switching circuit may be placed in a standby condition. The opening of break contacts BAS, BBS or BDS in the operating circuit of relay CA of switch- Aing section C prevents the actual operation of'switching ,section C and, therefore, the operation of transmitter -group C. Upon the completion of transmission by transmitter group B, switching section C Will be operated and transmitter group C will be placed in operation toforwa'rd Ya message overY the single channel of operation.; While single transmission line.

transmitter group C is "in operation, switching section'A ofthe switching circuit may be placed in standby condition. Upon the completion of transmission by transmitter group C, switching section A will be loperated and transmitter group A will be placed in operation to forward a message over the single channel of operation. While transmitterl group A is in operation, switching section B of the switching circuit may be placed in standby condition and so on.

The switching circuit of the transmitting control unit is, therefore, operatedl on two levels of activity to sequentially place the transmitter groups in operation. When transmitter group A is operating, transmitter group B may be prepared for subsequent operation and transmitter group C may not. The relays AA, AB and AD of switching section A of the switching circuit operate to prevent the actual operation of switching section B'of the switching circuit and, therefore, transmitter group B. When transmitter group A ceases operation, transmitter group B will be operated, transmitter group C may be prepared for subsequent operation and transmitter group A may not. The relays BA, BB and BD of switching section B of the switching circuit operate to prevent the actual operation of switching section C of the switching circuit and, therefore, transmitter group C. When transmitter group B ceases operation, transmitter group C will be operated, transmitter group A may be prepared for subsequent operation and transmitter group B may not. The relays CA, CB and CD of switching section C of the switching circuit operate to prevent the actual operation of switching section A of the switching circuit and, therefore, transmitter group A. When transmitter group C ceases operation, transmitter group A will be operated and so on. The first level of activity, namely, the operation of relay AH, A1, BH, B1, CH or C1 will determine the particular transmitter of'group A, `B or C which is to be placed in operation. It will also determine the transmitter group which may be placed on standby condition. The-second level of activity, namely, the operation of relay AA, BA or CA and the resulting operation of the contacts thereof in the operating circuits of the other relays will determine the particular one of the transmitter groups that is actually to be placed in operation.

It is not necessary that the transmitter groups be operated in the order recited above, namely, A, B and C.

If no message is made available in any of the remaining message transmitters during the operation of one of them, the switching circuit will be returned to its original condition as soon as an yoperating message transmitter has completed its transmission. Any of the message transmitters including the one just operated may be placed in operation. In this situation, only one message will be available for transmission4 at a time by thev message transmitters. The vswitching circuit, therefore, automatically and sequentially operates the transmitter groups in a predetermined order, namely, A, B and C, so long as a second message is made available for transmission by the insertion of a perforated message tape in the sensing con'- tacts of one of the message transmitters of one of th'e transmitter groups not already in operation, as determined by the particular transmitter group already in operation.

On the other hand, the switching circuit may be made to sequentially operate the transmitter groups in any order desired so long as the transmitter group in operation is permitted to complete the transmission of a message before a second message is made available for transmission by the insertion of a perforated message tape in the sensing contacts of one of the message transmittersof one ofthe other transmitter groups. S

It will be helpful at this point to review vthe discussion. The wiper 5 of selector control 6 is positioned at position l. The transmitters of transmitter groups A, B 'and -C are operated to sequentially transmit messages overa The operation of transmitter group A is controlled by switching section A of the switching circuit, transmitter group Bfby switching Section B of theA switching circuit and transmittergroup C. by switchingy section C of the switching circuit. The switching circuit is operated, in accordance with the positioning of the selector control 6. Only one of the switching sections of the switching circuit will be operated at a time and, therefore, only one of the transmitter groups will be opcrated at a time. Provision is made. for a predetermined one of the switching sections to be placed in a, standby .Condition during the operation of another one of the switching sections so that, immediately upon the completion of transmission b y the transmitter group in operation, the switching section placed in standby condition may be operated. Upon the operation of the switching section, a second one of the transmitter groupswill be operated to transmit a message over the single available transmission line. In this manner, the transmitter groups A, B and C may be continuously operated to sequentially transmit, messages over the single transmission line.

Referring to Fig. 2a, the distributing, contacts 44 of the routing transmitter 1, the distributing contacts 49 of the numbering transmitter 2', the distributing contacts, 52 of the message transmitter 3 and the distributing contacts S7 of the message transmitter 4 of transmitter group. A are connected in series byy lead 59V which completes a path from the positive terminal 9.3v of a. source of potential, not shown, to ground through the distributing contacts of the respective transmitters. of transmitter group A and the windingsv of a polar relay BA. The transfer contacts PAI of the polar relay PA include; an armature 1 and contacts 2 and 3. In the same manner, the distributing contacts of the four transmitters of transmitter group B are connected in series by lead 6.0 which completes a path from the positive terminal. 93 of a source of potential to ground throughthe distributing vcontacts of the respective transmitters of transmitter group. B and the windings of a polar relay PB. The polar relayl PB includes transfer contacts BB1 which include anarmature 1 and contacts 2 and 3. The distributing contacts of the f onrtransmitters of transmitter group` CV are connected in series by lead 61 which completes.- apathfrom the positive terminal 93 of a source of potential Vto ground through the distributing contacts ofthe respective transmitters of transmitter group C and the windings of'polar relay PC. The polar relay PC includes transfer contacts PCl of the same type as those of polar relays PA and PB. It will be remembered that the wiper 5 of selector control 6 is positioned on control position 1. Therefore, selector switches 29 through 34 are also set on position 1. A path will be completed from output terminal 62 r to output terminal 63 through lead 68, contact 3 and armature 1 of transfer contacts` PC1 of polar relay PC, lead 69, wiper 5 and position 1 of selector switch 29, lead 70, contact 3 and armature 1 of transfer contacts PBI o f polar relay PB, lead 71, wiper 5 and position 1 of selector switch 32, lead '72, contact 3 and armaturel of transfer contacts PAI of relay PA, lead 73, wiper 5 and position l of selector switch 34 and lead 74. Transmission line 7 is connected to terminals 62 and 63. Transmission line 7 is, therefore, connected` to the output circuits of all of the transmitters through the transfercontacts PAI of polar relay PA, PBI of: polar relay PB and PCI of polar relay PC. As the transmitters of transmitter group A are sequentially operated, each transmitter will operate polar relay PA in accordance with the intelligence to be transmitted by that transmitter, namely, routing, numbering and message. The operation of polar relay PA will operate transfer contacts PAI ofthe relay. Armature 1 of the transfer contacts PAI will be driven between contacts 2 and 3 of the transfer contacts in accordance, with the intelligence` transmitted by' the` transmitters of'transmitter group A. The operation of the transfer contacts PAl of polar relay PA willy key transmission line 7 and a message will be transmitted thereover. As the transmitters of transmitter group B are also 15 sequentially operated, transfer contacts PBl of polar relay PB will key transmission line 7 in accordance with the intelligence fed to polar relay PB. When the transmitters of transmitter group C are sequentiallyyoperated, transfer contacts PCI of polar relay PC will key transmission line 7 in accordance with the intelligence fed to polar relay PC. The messages from each of the groups of transmitters A, B and C will be sequentially transmitted over the single transmission line 7.

Transmission line 8 may now become available for use in addition to transmission liuc 7. -It will. first be assumed that the volume of traffic being handled by transmitter group A justifies the use of an individual transmission line for that transmitter group. The wiper 5 of selector control 6 will be positioned on control positionl 2. Selector switches V2() through 34 will Aautomatically be set ou position Z by theV operation of shaft 35. A perforated message tape is inserted in the sensing contacts of one of the message transmitters 3 or 4 of transmitter group A, The availability of a message for transmission will .be registered in switching section A of the switching circuit by the operation` of relay AH or AL depending upon` which` of the message transmitters 3 or 4 is used. Uponthe operationV of one of the relays AH or AJ, make contacts AHI of relay AH or make contacts A11 of re lay AJ will close completing, a path from ground to the positive terminal 92 through the closed one of the oontacts, armature 1 and contact 3 4of transfer contacts AC3 of relay AC, armature 1 'and contact 3 of transfer contacts A1333 of relay AE, break contacts AG2 of relay AG, the winding of relay AA, wiper 5 and position 2 of the selector switch 20, lead and lead 76. Relay AA will be energized. Relays AB and AX will then be energized in the same. manner, as was previously described. Instead of; relay AC being energized to energize the windngof the. release, magnet 42 of the routing transmitter 1 of; transmittergroup A by the closing of make contacts AC4. of relay AC., 'as previously occurred, a path will nowbe completed from the positive terminal 92 to ground through lead 38,V make contacts ABI of relay AB, position 2,; of selector switch 21, lead 77, break contact AC1 of relay AC, armature 1 and contact 2 of transfer contacts AE1 of relay AF, the winding of relay AE, lead 45 and; closed contacts 46` of numbering transmitter 2 of transmitter group A. The sequence of operation of switching section A of the switching circuit will, thereafter,l be the, same as previously outlined except that routingtransmitter 1 of transmitter group-A hasv not been operated.

The reason for lay-passing the operation of the routing transmitter may be found by examining the output circuit of transmitter group A. When the wipers S of the selector switches. 29 through 34 are set on position 2, contact 3 of transfer contacts 'PAI of polar relay PA will be, connectedv to terminal 66 via lead 72, lead 78 wiper 5 and positionA 2 of selector switch 33 and lead. 79. Armature- 1 of transfer' contacts PAI of polar relay PA will be connected to terminal 67 via lead 73, wiper 5 and position 2 of selector switch 34 and lead 80. Transmission line 8 is connected to terminals 66 and 67. The full capacit-y of transmission line 8Y will be occupied by messages transmitted by transmitter groupA. As separation of the line into a plurality of message channels at the receiving station is notnecessary, the routinginformationA will be of no value. Provision, therefore, is made inthe switching section A to by-pass the operation of the-routing transmitter oftransmitter group AY when` the wiper 5 of selector control 6. is set on positionv 2.

A second message may be inserted in the sensing contacts of `one ofthe message transmitters 3 or 4Y of transrnitter group B. The availability of the message for transmission, will be registered in switching section B of the switchingcirouit bythe operation of relay BH or BJ'. Upon the operation of one of the, relays, a, patlr will be completed from ground to the positive terminal 92 through the closed make contacts BH2 of relay BH or make contacts B12 of relay BI, Aarmature 1 and contact 3 of transfer contacts BC3 and relay BC, armature 1 and contact 3 of transfer contacts BE3 of relay BE, break contacts BGZ of relay BG, the winding of relay BA, wiper and position 2 of vselector switch 23, lead 81, -break contacts CD1 of relay CD, break contacts CB1 of relay CB and break contacts CA1 of relay CA. Relay BA will be energized and switching section B will operate to control sequentially the operation of the transmitters of transmitter group B.

A third message may, then, be inserted in the sensing contacts of one of the message transmitters 3 or 4 of transmitter group C. The availability of the message for transmission will be registered in switching section C by the operation of relay CH or CJ. Upon the energization of either relay CH or CJ, a path will be completed from ground to the winding of relay CA through closed make contacts CH2 of relay CH or make contacts C12 of relay CI, 'armature 1 and contact 3 of transfer contacts CC3 of relay CC, armature 1 'and contact 3 of transfer contacts CES of relay CE, `and break contact CGZ of relay CG. The winding of relay CA is connected to the positive terminal 92 through wiper 5 and position 2 of selector switch 26, break contacts BD3 of relay BD, break contacts BB3 of relay BB and .break contacts BA3 of relay BA. When switching section B is operated, contacts BA3 of relay BA, BB3 of relay BB Iand BDS of relay BD will open in that order, contacts BD3 of relay BD remaining open due to the continued energization of relay BD so long yas transmitter group B is transmitting a message. Because the operating circuit of relay CA is broken by the opening of the contacts of relays BA, BB and BD, relay CA cannot operate. Therefore, 'so long as transmitter group B is in operation, switching section C of the switching circuit cannot operate and cannot bring -about the operation of transmitter group C.

It will be remembered that the -break contacts CD1 of relay CD, break contacts CB1 of relay CB and break contacts CA1 of relay CA are included in the operating circuit of relay BA of switching section B of the switching circuit. Therefore, when switching section C is operating, at least one of these contacts will be open and relay BA cannot be energized. 'Switching section B, therefore, cannot operate so long as switching section C of the switching circuit is operating and controlling the operation of transmitter group C. Transmitter group B cannot be operated so long :as transmitter group C is operating.

Reference was made earlier to the iirst level of activity in each of the three switching sections A, B and C of the switching circuit. Attention is now called to selector switch 22 in switching section A, selector switch 2S in switching section B and selector switch 28 in switching section C of the switching circuit. When the wiper 5 of lselector control 6 is set on position 2, the wiper 5 of each of these switches will automatically be set on position 2. When the wiper 5 of selector switch 22 is set on position 2, la path is completed from the positive terminal 92 to the windings of relays AH :and AJ via lead 38, lead 91, lead 82, wiper 5 and position 2 of selector switch 22, lead 83 and the transfer contacts AH2 of relay AH and A32 of relay AJ. The break contacts B11 of relay BJ vand lbreak contacts BH1 of relay BH are by-passed. Relays AH and AJ may be operated regardless of the condition of these contacts. Selector switch 25 in switching section B operates the same way. The break contacts CJ 1 of relay C] and break contacts CHl of relay CH are bypassed and relays BH and BI may be operated regardless of the condition of these contacts. Selector switch 28 in switching section C `also operates in the sameV way. The break contacts A14 of relay AI and AH4 of relay AH are by-passed and relays CH and CI may Ibe operated regardless of the condition of these contacts. There is no control exercised at the first level of activity while the wiper 5 of the selector control 6 is set on position 2.

'I'he reason for eliminating the rst level of activity when the selector control 6 is set on position 2 is apparent. It will be remembered that when all three transmitter groups A, B and C are being sequentially operated'and switching section A is in operation, switching section B may be placed on standby condition and switching section C may not be operated in any way. When switching section B is in operation, switching section C may be placed in standby condition and switching section A may not be operated in anyway. When switching section C is operated, switching section A may be placed on standby condition nad switching section B may not be operated in any way. When the selector control 6 is set on position 2, however, the switching circuit will be operated to interlock the operation of switching sections B and C only. Switching section A operates independently and is not controlled in any way by the operation of switching sections B and C. It is necessary, therefore, to effectively remove this level of activity from the switching circuit to permit only the switching sections B and C to be sequentially operated. As pointed out above, when all three transmitter groups are operated sequentially and switching section B is in operation, switching section C may be placed in standby condition. However, when switching section C is in operation, switching section B cannot be operated in any way. It has already been shown how the operation of selector switch 22 removes any control over relays AH and AJ of switching section A by the other switching sections. This, of course, is necessary to permit the complete independent operation of switching section A and, therefore, that of transmitter group A over transmission line 8. The operation of the selector switches 22, 25 and 2S remove from the operating circuits of relays AH, AJ, BH, BJ, CH and CJ the respective break contacts of the relays. The only control exercised over the switching circuits is therefore the interlocking contacts of switching sections B and C on the second level of activity referred to above, namely, the controlled operation of relays BA and CA.

It has already been mentioned that the routing transmitter of transmitter group A will not be operated due to the setting of selector switch 21 in switching section A of the switching circuit on position 2. It would be well to note that the selector switches in switching sections B and Ccorresponding to selector switch 21 in switching section A, namely, selector switch 24 in switching section B and selector switch 27 in switching section C, when placed on position 2 bring about no change in the electrical arrangement of the respective switching sections. Position 2 and position 1 of switch 24 are connected together, as are the same positions of switch 27. The switching sections will operate in the same manner as before, including the operation of the routing transmitters. Transmitter groups B and C are sequentially operated over transmission line 7 and the routing information is necessary to control the distribution of the messages transmitted by the respective transmitter groups at the receiving station.

The output circuits of the transmitters of transmitter group A will be connected to an individual transmission line 8 and, as only the transmitters of transmitter group A will be transmitting over line 8, there is no need for routing information. For this reason, the routing transmitter of transmitter group A is not operated during the operation of section A of the switching circuit with the control 6 in position 2. As for transmitter groups B and C, a path may be traced from terminal 62 to terminal 63 via lead 68, Contact 3 and armature l of transfer contacts PCI of polar relay PC, lead 69, wiper 5 and contact position 2 of selector switch 29, lead 70, contact 3 and armature 1 of transfer contacts PBI of polar relay PB, lead 19 line T. Linel 7 will be keyed' by the transfer contacts PB ofpolar relay PB which is connected to the output circuits of the transmitters of transmitter group B'via lead 60 and' the transfer contacts PCI of polar relay PCY which is connected to the output circuits of the transmitters of transmitter group C via lead'61.

It may now be desirable that transmitter group B' be connected to the individual transmission line 8 and that transmitter groups A and C be sequentially operated over transmission line 71 The wiper 5 of the selector control' willbe positioned at position 3. Simultaneously,

the wipers of selector switches 20 through 34 will also be positioned at position 3' of the respective switches. A perforated message tape may, then, be inserted; in the sensing contacts of one of the message' transmitters 3 or 4 of' transmitter group A. The availability of the message is registered in switching section A ot" the switchingl circuit' by the operation oeither relay. AH or AJ', respectively. Upon the operation of either relay. AH' or AI,

a path will be completed from ground to the positive terminalV 92 through either make contacts AHIl of relay or make contacts All. of'relay Al, armature l and. contact 3" oftransfer contacts AC3 ot'relay AC; armature 1' and contact 3 of transfer contacts AES' of relay AE, break contacts AGZ of relay AG', the winding of` relay AA, wiper 5' and' position 3 of'selector switch 20; break contacts CD1 of relay CD, break contacts. CB1 of relay CB and break contacts CAI ofrelay CA. Relay AA will be energized and' switching section A of the switching circuit will operate to sequentially control the operation of the transmitters oftransmitter group A. When the wiper 5 of selectorV switch 21 is positioned at position 3 of the switch, following the operation of relay AX and AB, a pathA will once again be completed from the positive terminal 92 to ground through. lead 38,' malte contact ABI' of relay AB, wiper 5 and position 3 of selector switch 21', lead 41',A armature 1 and contact 2` of transfer contacts ADI of relay AD, the winding of relay AC, lead 40 and closed contacts 39 of the routing transmitter i. of transmitter group A. Relay AC will be energized and the Winding of' the release magnet 42 of the routing transmitter will be energized by the closing of make contacts AC4 of relay AC. The remainder of the transmitters of transmitter group A will' be sequentially operated by switching section A of the switching circuit, as previously outlined'.

A secondperforatedV message tape maybe inserted in the sensing contacts ot" one of the, message transmitters 3 or 4 of 'transmitter group B. TheA availability of' the message for transmission will be registered by the operation of relay BH or BJ in switching section B` of. the switching circuit; Upon` the operation ot either relay BH or Bl, a path will be completed from ground to the positive terminal 92 through make contacts BH2 of relay BH ormake contacts BF2 of relay BI, armature 1 and contact 3` of transfer contacts BC3 or relay BC, armature l' and contact 3 of transfer contacts BES of relay BE, break contacts BG?. of relay BG, the winding of relay BA, wiper 5 and position3V ofselector switch 23, lead 85 andlead 76. Relay BA will be energized and switching section B of the switching circuit will be operated to sequentially operate the transmitters ot4 transmitter group B. Following the operation of relay BA, relays BX and BB'gwill be operated. Upon the operation of relayv BB, a path will be completed from the positive terminalV 92 to ground through a circuit including wiper 5 and position 3 of selector switch 24 and the Winding of relay BE. When relay BE is energized, the winding of the release magnet 47 ofthe numbering transmitter 2 of transmitter group B will be. energized and the numbering transmitter will be placed in operation. The sequence of operation of switching section B of. the switching 'circuit will continue `and the transmitters of' transmitter group B, with the exception of the routing transmitter, will be sequentially operated, as

`outlined above. The operationof the ,routing transmitter is prevented bythe setting of' wiper-5jv of selector switch 24' on position 3;. thereby, energizing' relay BE and bypassing the operation of relay BC which wouldJ normally occur., Transmitter group B may, therefore, be. operated.'

theenergization of, one of the relays, a path will be. completed from ground tothewinding' otre-lay CAthrough` either` malte contacts CHgor relay' CH or. make contacts C12' of relay` CI', armature L and` contact 3 ofL transfer contacts' CCS ofrelay CC, armature i' and Contact 3' of transfer contactsA CEB of relay CE and breakj contact CGZ of relay CG. The winding of relay CA wili be connected to' the positive terminal; 92' through wiper 5 and' position 3j of selector switch 26,. lead 86, break contacts ADS ofrelay AD, break contacts ABS of relay AB, break contacts. AA3 ot' relay AA and leady 76. The sequence.- of operation of switching section A of the switching circuit is such as that at least one of the break contacts ADT, ABS` or AAE'l will be open during the operation of theswitching section A to control'the operation of'transmitter group A. Relay CA cannot, therefore, be operated so long as transmitter group. A is. being operated' byV switching sectionY A Vof the switching circuit; Because relay CA cannot be operated', transmitter group C' cannot beoperated by the operation of switching section C ofthe switching circuit; It" switching section C should be placed in operation before switching section A of the switching circuit by the insertion of a message tape in the. sensing contacts of one off the message transmitters or transmitter group C, the operation of switching section C will' prevent Athe operation of' switching section A bymaintaining at least one o f the break contactsCDi of relay. CD,.break contacts CB1' of relay CB or break contacts'CAIlv off relay CA connected in the operation circuit of relay;V AA in open.. condition. therefore, cannot be operated so long as transmitter group Cv is in operation.

The wipersS'oftheselector switches 29 through 3.6iwill be. set onvporsition. 3' ot` the switches. Terminal 62j will be connected'to terminal'63 via lead 68, contact 3 andv armature 1.0i transfer. contectsPCl 0f Polar relay PC, lead 69, wiper 5 andposition 3 of selector switch 29, leadS'l, lead 72,` contact 3 and armature 1 of transfer contacts PAl of'polar relayV PA, leadj 73, wiper 5: and position 3 of selector switch 34 and' lead 74. Transmission line 7 is connected through terminals 62 andy 6,3 to the transfer contacts PCI of polar relay PC and transfer contacts PAl of. polar relay-PA. The operation ofthe polar relay PA by the operation of'thetransmitters of transmitter group A via lead'59 and the operation of' the polar relay PC by theoperation of the transmitters ot transmitter group. C via .lead 61 will serve to forward messages by the operation oflthe transfer contacts BA1 and' PCI over the line 7. The switching circuit of the transmitting control unit will be operated so that` transmitter. group. A and transmitter group 'C will be operated to sequentially transmit messages over line 7; Terminal 66 will be connected to terminal' via lead' 79,3 wiper 5' and position 3 of selector switch 33.', lead 70,.' contact 3 and armature l of transfer contacts BB1 otpolar relay PB,lead 71", wiper 5 and position .3- of selector switch 3,2, 'lead SS and lead 80. Transmission line l8 isl connected through terminals 6ta and 67 tojthe -transt'er contacts P131Y of polar relay. PB. Polar relay PB` will be operatedinaccordance with the messagesforwarded-to-the relay va-162x460, by the. transmitters-of transmitterfsroup.; The oper-@H611 of Polar relayl B13-will, of course, key the-transmission line 8. by

Transmitter group- A,y

comme the operation of the transfer contacts PBI associated therewith. The full capacity of the transmission line 8 will be occupied by the messages forwarded thereover by transmitter group B. As only one of the transmitter groups transmits over the line, there is no need for the routing information to be forwarded by the routing transmitter 1 of the transmitter group. As has been pointed out, switching section B of the switching circuit will be operated so that the routing transmitter 1 of transmitter group B will not be placed in operation.

Referring to selector switch 22 of switching section A, selector switch 25 of switching circuit B and selector switch 23 of switching section C, position 3 of each of the switches is connected directly to position 2 of the respective switches. When selector control 6 is set on position 3, the only control exercised by the switching circuit will be the interlocking control brought about by the operation of the relays of switching sections A and C. Switching section B will be independently operated and no control will be exercised thereover by the other switching sections. As position 3 and position 2 of each switch are connected together, the same condition will exist as did when selector control 6 was set on position 2. The only control exercised by the switching circuit will be on the second level of activity, namely, the interlocking control brought about by the operation of relay AA of switching section A and relay CA of switching section C.

During certain periods, all three transmission lines 7, 8, and 9 may become available for use and the volume of traiiic handled 'by the system lmay warrant the use of all three lines. The wiper of selector control 6 is set on position 4. Simultaneously and automatically, the wipers S of the selector switches through 34 will be set on position 4 by the operation of the common drive shaft 35. A perforated message tape is then inserted in the sensing contacts of one of the message transmitters 3 `or 4 of transmitter group A. The availability of a message for transmission will be registered in switching section A of the switching circuit yof the transmitting control unit by the energization `of either relay AH or AJ, depending upon the message transmitter used. The energization of relay AH or AJ will complete a path from ground to the positive terminal 92 through the make contacts AH1 of relay AH or make contacts All of relay Al, armature 1 and contact 3 rof transfer contacts AC3 of relay AC, armature 1 and contact 3 of transfer contacts AES of relay AE, break contacts AGZ of relay AG, the winding of relay AA, wiper 5 and position 4 of selector switch 20, lead 75 land lead 76. Relay AA will be energized. Position 4 of f selector switch 21 is connected to position 2 of the of the switch. Therefore, the -selector switch 21 will again be arranged in the switching section A in the same manner as when the wiper 5 of the switch is set on position 2. It will be remembered that when the switch is set on position 2, the routing transmitter 1 of transmitter group A will not be operated, the switching -section A operating to sequentially operate the transmitters of group A starting with the numbering transmitter 2 of the group.

A second message tape may be inserted in the sensing contacts of one of the message transmitters 3 or 4 of transmitter group B. The availability of the message for transmission will be registered in switching section B by the energization of relay BH or BJ. Upon the energization of one of the relays, Aa path will be completed from ground to the positive terminal 92 through make contacts BH2 of relay BH or make contacts BIZ of relay Bl, armature 1 and contact 3 of transfer contacts BC3 of rel-ay BC, armature 1 and contact 3 of transfer contacts BE3 of relay BE, break contacts BGZ of relay BG, the winding of relay BA, wiper 5 and position 4 of -selector switch 23, lead S5 and lead 76. Relay BA will be energized. Position 4 of selector switch 24 is connected to position 3 of the switch and the switch will be arranged in the switching section B in the same manner as when 22 the Wiper 5 of the switch is set on position 3'. The rout'- ing transmitter 1 of transmitter group B will not be operated and the switching section B will be operated to sequentially operate the transmitters of transmitter groupV B starting with the numbering transmitter 2 of the group.

A third message tape may be inserted in the -sensing contacts of one of the message transmitters 3 or 4 of transmitter group C. The availability of the message for transmission is registered in switching section C of the switching circuit of the transmitting control unit by the energization of either relayV CH or Cl. Upon the energization of one of the relays, a path will be completed from ground to the positive terminal 92 through make contacts CH2 of relay CH or make contacts C12 of relay CJ, armature 1 and Vcontact 3 of transfer contact CCS of relay CC, armature 1 and contact 3 of transfer contacts CES of relay CE, break contacts CG2 of relay CG, the winding of relay CA, wiper 5 and position 4 of selector switch 26, lead 89 and lead 76. Relay CA will be energized. Selector switch 27 will be arranged in switching section C in the same manner that selecting switch 24 is connected in switching section B and selecting switch 21 is connected in switching section A. The relays of switching section C will be operated in the sequence previously outlined in connection with switching sections A and B to sequentially operate the transmitters of transmitter group C starting with 4the numbering transmitter 2 of the group. As in the case of transmitter groups A and B, the routing transmitter of transmitter group C will not he operated.

Selector switches 22, 25 and 28 of the respective switching sections A, B and C will be set on position 4. Position 4 is connected to position 2 and 3 on each of the switches. There will be no change in the operation of the switching sections by setting these switches Yto the new position. The switching sections will exercise no control over one another, each section operating independently from the others. As all three switching sections may be operated Y simultaneously due to the absence of any interlocking control on the second level of activity, namely, the control of the operation of relays AA, BA and CA, transmitter groups A, B and C may be operated simultaneously, sequentially or in any time `relation or order desired.

Terminal 62 will be connected to terminal 63 via lead 68, contact 3 and armature 1 `of transfer Icontacts PC1 of polar relay PC, lead 69 and wiper 5V and position 4 of selector switch 29. Terminal 64 will be connected to terminal 65 via lead 90, wiper 5 and position 4 of selector switch 30, lead 70, contact 3 land armature 1 of transfer contacts PBI of polarrelay PB, lead 71, wiper 5 and p0- sition 4 of selector switch 32, wiper 5 `and position 4 of selector switch 31 land lead 91. Terminal 66 will be connected to terminal 67 via lead 79, 4wiper 5 and position 4 of selector switch 33, lead 72, contact 3 and armature 1 of transfer contacts PA1 of polar relay PA, lead 73, wiper 5 and position 4 of selector switch'34 and lead 80. Transmission line 7 will be connected to the output cir-cuits of the transmitters of transmitter group C through the operation of the transfer contacts PCI of polar relay PC.V

Transmission line 8 will be connected to the output -circuits of the transmitters of transmitter group A through the operation of transfer contacts PA1 of polar relay PA andV transmission line 9 will be connected to the output circuits of the transmitters of transmitter group B through the operation of the transfer contacts PBll of polar relay PB. Each -of the transmitter groups will be connected to an individual transmission line. As individual transmission linesare assigned to each transmitter group, it is not necessary to control the operation thereof Aas in multiplex transmission and the transmitter groups may be independently operated in .any order desired.

A further feature of the telegraph system of the invention should be mentioned at this time. During the operation of the transmitter groups, it is now and then necessary to transmit information other than the regular message traftc. Such information may be in the nature of operating instructions and soforth. 'Referringtoswitching section A of the switching circuit, shown in Fig, 2b,

of the transmitting control unit, a push'bu'tton95 isco'n'- nectcd in'series'with thewinding of relay A'F. LWhenthe switching 'section A is in operation controlling the operation of transmitter group A, the push'button 9S will be pressed. When relay AA operates 'in the sequence Vof operation of the switching section A, a path will'be completed from.'ground to the positive'terminal .92 'through the closed contacts of pushbutton '95,make contacts AAil of relay AA and the 'winding of relay AF. Relay AF will be energized and will be self-locked 'by the closing of make contacts AF2. of `the relay. It Will'be remembered that'the operation "of the numbering'transmitter required the energization of relay AE. The :energization of relay AF by the push button 95 will cause relay AG to be energized in any sequence in place of relay AE. As relay AE is notenergized, transmission from the numbering transmitter ofthe transmitter group A will be withheld. The makecontacts AAl of relay AA in 'series with the push 'button 95 prevent the inadvertent operation of the push button from being effective. The push button is etectiveonly during the operation ofthe switching section A -and during the operation of relay A push button'93 is connected inseries with the winding of relay BF in switching section'B vand a push button 94 is connected in series with the winding 'of relay CF in switching section C. Push buttons -93 and 94 will operate in the same manner as does push button95'in therswitching section A. The push buttons 95, 93 and k94' may, therefore, be used to prevent transmission from the numbering transmitters included in each of the transmitter groups. It is clear that the use ofeach ofthe push buttons is individual to the switching section in which it appears` The operation of one ofthe push buttons serves to prevent the operation of thenumbering transmitter ofthe transmitter group controlled 4by the particularswitching section in which the push button appears. The operation of the switching circuit 'of the transmitting control unit is affected by the operation of the push buttons in no other way.

To review the operation of the transmitting control unit as shown in Figs. 2a, 2b, 2c and 2d, when the wiper of selector control 6 issetV at position Lswitching sections A, B and' C of the unit will'be interlocked so that the transmitter groups A, B and Cwill'be operated to sequentially transmit messages over the single transmission line Y 7. At position 2 of selector control 6, switching section A will operate transmittergroup A to'transmit messages over transmission line '8. Switching sections B and C will be interlocke'd Aso that transmitter groups B andC will sequentially transmit messages overltransmission line 7. At position 3 of the selector control l6, switching section B will operate transmitter group B to transmit messages over transmission line 8. Switching-sections A and C will be interlockedso that transmitter groups A and C will sequentially transmit messages over transmission line`7. At position 4 of the selector control 6, switching section A will operate transmitter 'group A to transmit messages over transmission line '8. "Switching-v section B will operate transmitter group B to transmit messages over transmission line'9 and switching section C will operate transmitter-group C to transmit messages over transmission Yline 7. A

Reference will now be made to Figs. 4a and lv4b which disclose one embodiment of a receiving terminal -'station that may be used in the telegraph system of the invention, shown in the block diagram of Fig. l. Fig. 5 depicts the mannerin which Figs.V 4a and 4b are to be assembled. The operation of thereceiving-director VUnit is based on the fact that, when `at least two of the transmitter groups A,'B and Care operated to collectively and sequentially transmit messages overa single transmission line, the messages from 4each transmitter group will be precededby routing information'indicatingthe des- 5j2a tnation'ofeachof the messages so transmitted. It will be assumed that each of the three transmitter groups is set to transmit messages to diierent destinations. The messages transmitted by transmitter group A will be sent to one destination. The messages transmitted by transmitter group B will 'be sent to another ldestination and the messages transmitted by transmitter group C will be sent to still another destination. The routing information transmitted by the routing transmitter 1 of transmitter group A will indicate the destination of the messages transmitted by message transmitters 3 and 4 of the group. In the same manner, the routing informationtransmitted by the routing transmitters of transmitter groups B and C will indicate the destination of the messages transmitted by the message transmitters 3 and 4 of each ofthe transmitter groups B and C. The make-up of the routing information so transmitted is, of course, a matter of choice. The receiving director unit may be constructed to respond to any information, "which will act as routing information, to control the distribution of messages transmitted over a single transmission line among a plurality of receiving devices. It is desirable, however, that the routing information include a sequence of code characters which do not normally appear in the regular message traic transmitted over the line. By using such a combination of characters, the receiving director unit will not be accidentally operated due to the reception of the character or characters included in the routing information during the reception of'a message, as transmitted by one of the messagetransmitters at the transmitting station. In the receiving director unit to 'be described, the routing information transmitted `by each of the routing transmitters comprises a series of eight characters. The firstive of these characters 'consist 'of signals'whose 'function is to disconnect the'sin'gle transmission line from its previous termination. The nextt'wo 'characters function to lagain terminate theltransmission line in accordance with their construction, and the'remaining character performs local functions at the yreceiving 'director unit. The tirst 'five characters of the routing information Will, hereinafter, be referred to 'as the disconnect signal. in the instant case,\the disconnect signal will consist of 'the character sequence figure shift, Z, Z, Z, ligure shift. The character combinations CP, BM and JI have Vbeen chosen Vas `directing character combinations to act as a connect signal to re-establish the proper termination of the line-at the-'receiving vdirector unit. The eighth character willfbe the lcharacter letters shift to 'bring the receiving devicesat the receiving station into the lower case. `The Vrouting transmitter of transmitter group A will be set to repetitiously transmit the disconnect vsignal plus the directing character combination Bh/l.y The routing transmitter of transmitter group i3 will be set to repetitiously' transmit the disconnectI signal plus the directing character'combination CP and the routing transmitter of transmitter 'group C will be set to repetitiously transmit the disconnect signal plus the directing Acharacter combination 'JIT lAs discussed in connection with the block diagram of Pig. l,-the receiving director unit l1 includes a selector control 16 comprisinga wiper 5 and four positions. The four positions of the selector control le of the receiving director unit'l 'conrespo-nd'to the 'tour control positions of Athe selector control 6 of the transmitting control unit 9d. As shown `in Figs. 4a and 4b, theselector control 16 comprises iiftee'n 4 selector 'switches 93 through T14. Each of the selector switches includesa-wiper `5 4and four positions. The wipers I5 of all the selector switches are mounted on and drivenfby a common drive shaft 115. As the wiper S of selector control 16 is rotated'from one position to the lneXt,the wipers 5 of the selector switches 100 through l-i will also, simultaneously and automatically, 'be rotatedfrom one' position of therespective'Jsw-itc-hes to thenext. When selector control 

